Sewing machine



Oct. 1, 1940. N. v. CHRISTENSEN ET AL 2,216,700

SEWING MACHINE Filed Nov. 18, 1955 4 Sheets-Sheet 1 WITNESSES.- INVENTORS:

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1940- N. v. CHRISTENSEN ET AL 2,216,700

SEWING MACHINE Filed Nov. 18, 1955 4 Sheets-Sheet 2 FIG 12:

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INVENTORS.

1, 1940. N. v. CHRISTENSEN ET AL 2,216,700

SEWING MACHINE Filed Nov. 18, 1955 4 Sheets-Sheet 5 WI TNESSES: INVENTORS:

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SEWING MACHINE Filed Nov. 18, 1955 4 Sheets-Sheet 4 157a, ll

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WITNESSES: I N VE N TORS:

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$610; I ORNEYS.

Patented on. 1, 1940 SEWING MACHINE fNoi-man V. Christensen, Chicago, and George Sauer, Berwyn, Ill., assignors to Union Special Machine Company; Chicago, 111., a corporation of Illinois Application November 18, 1935, Serial No. 50,392 17 Claims (01. 112-215) This invention relates .to sewing machines; and it has reference more particularly to rotary hook sewing machines.

In sewing machines generally, certain of the machine elements, such for example as the feed dogs, having both endwise and lateral motion, are ordinarily operated by eccentrics grouped on a rotating shaft, while in sewing machines of the specific type referred to, the rotary hooks revolve twice during each stitch-forming and feed cycle. Under these circumstances, excessive friction takes place between the eccentrics and their straps, as well as between the rapidly rotating rotary hook shafts and their bearings, with attendant generation of excessive heat, which, in addition to the vibration due to the relatively heavy eccentric straps and rods, causes rapid wear of the parts with thenecessity for frequent replacements, and moreover has a limiting effect upon the speed at which the machines can be safely operated.

Our objection is directed toward overcoming these drawbacks, that is to say, we aim to minimize as far as possible, the friction and vibration of the parts, which object we realize in practice as hereinafter more fully set forth, by employing in sewing machines generally separate synchronously-rotating shafts with end cranks and relatively light pitmans in lieu of eccentrics and having strap links for imparting the feed and lift movements to the feed dog, and in rotary hook machines, by mounting the rotary hook shafts in addition, in sleeves driven in the same direction as said hook shafts but slower, so that the wear is evenly distributed between the hook shafts, the sleeves, and the bearings in which said sleeves are journaled.

A further aim of our invention is to make it possible, when compactness-of structure is desirable, to utilize the rotary hook shaft sleeve in a sewing machine organized as above, as a means for imparting the up and down or lifting movements to the feed do with attendant minimization of vibration in said dog when the machine Fig. III is a' fragmentary longitudinal section taken as indicated by the arrows III-III in Fig. I.

Fig. IV is a detail section taken as indicated by the arrows IV--IV in Fig. I. 5 f

Figs. V and VI are views similar to Figs. I and II showing an alternative embodiment of our invention; and

Fig. VII is a longitudinal section taken as indicated by the arrows VII-VII in Fig. V.

Referring first to the embodiment of our invention shown in Figs. I-IV of these illustrations, I designates the work support or bed plate of the machine, said support being of the usual rectangular configuration. Pendant from the work support I is an integrally formed bearing projection 2 which affords jounal support for the left hand end of a transmission shaft 3, as well as for a parallel auxiliary shaft 4 carrying the rotary hook which is indicated at 5, and another 29 parallel auxiliary shaft 6 of which the function will be later on explained. In the present instance, the auxiliary shafts t and 6 are disposed at one side of the transmission shaft 3, but it is to be understood that they may be otherwise ar- 25 ranged if desired or found more convenient. The feed dog 1 of the machine is secured, with capacity for vertical adjustment, to the outer end of a feed bar 8 by means of a screw 9, said feed bar being pivotally connected at iii to a rocker arm 30 H on a shaft I 2 fulcrumed for. oscillation in spaced bearing lugs l3 and it of the work support I.

For the purpose of imparting the endwise horizontal or feed movements to the feed dog I in accordance with our invention, we form 611, or afiix to the end of the transmission shaft 3, a crank i5 having a relatively smallwrist pin l6, and couple said crank with the rocker it by means of a link I! composed of telescoping parts 40 or sections 88 and iii. The mechanism illustrated for regulating the stroke of the feed dog I is of well known construction, and, as shown, includes a regulating shaft 20 which also has journal support in the pendant bearing projection 2 of the bed plate I. Hung from an arm 2! on the regulating shaft 20 is a lazy bar 22, which, at its lower end, engages a lateral stud 23 on the section I9 of the coupling link i'l. Thus, by turning the regulating shaft 20 to change the angle of the arm 21, the stroke of the feed dog I may be increased or decreased asdesired.

In sewing machines as heretofore constructed, up and down movements were imparted to the feed dogs by eccentrics mounted on the transmission shaft. However, in order to overcome the objections hereinbefore advanced in connection with the use of eccentrics, we provide the auxiliary shaft 8 at its outer end with a crank 25, which, like the crank l5, has a relatively small wrist pin 28. As shown in Figs. II and III, this wrist pin 26 is coupled, by means of a droplink 21, with a downwardly and forwardly reaching curved arm 28 of the feed bar 8. By virtue of the connection of the link 28 to the forward portion of the feed bar 8 immediately below the feed dog 1, the vertical movement is imparted more direct than when the connection was made, as heretofore, between an eccentric on the transmission shaft 3 and an intermediate point on said bar. in the bar 8 and the action of the feed means thereby rendered easier and more quiet.

It is of course essential that the auxiliary shaft 6 be driven at synchronous speed with the transmission shaft 3. Accordingly, we have fitted the transmission shaft 3 and the auxiliary shaft 6 with spur gears 29 and 30, and intenposed between said spur gears an intermeshing idler gear 3| which is secured to'a sleeve 32 surrounding the rotary hook shaft 4 so that said sleeve partakes of the rotary motion at a corresponding speed from the transmission shaft 3. As shown, the sleeve 32 is Journaled in a bushing 33 set into the bearing bracket 2; while the rotary hook shaft 4 extends to the right beyond the gear wheel 3| into a supplemental bushing 35 also set into the bearing projection 2. Affixed to the rotary hook shaft 4 in the interval between the gear 3| and the :bushing 35 is a spur gear pinion 36 which meshes with a spur gear wheel 31 of twice the size secured to the transmission shaft 3. Accordingly, the rotary hook shaft 4 is caused to revolve through two rotations for each feed movement of the dog I.

From Figs. I and III it will be observed that the gear wheels 293l and 36, 31 are housed in a hollow 38 formed in the bearing bracket, said hollow being closed at the bottom by a removable plate with resultant provision of a sump for lubricating oil. Some of the oil splashed by r0- tation of the gears 293| and 36, 31 in the sump finds its way to the portions of the rotary hook shaft 4 respectively in the sleeve 32 and the bushing 35, as well as to the bearings for the transmission shaft 3 :and the auxiliary shaft 6. The outer surface of the sleeve 32 is lubricated by oil introduced from above into oil holes 39 (Fig. IV) in the work plate.

By use of separate shafts having end cranks with small wrist pins for imparting the feed and lift movements to the feed dog, it will be apparent that we have not only decreased the friction and the weight of the parts, but have rendered said parts more convenient of access for assembling and adjusting. Moreover, by interposing the sleeve 32 between the rapidly revolving rotary hook shaft 4 and the bearing bushing 33, and by rotating said sleeve in the same direction at half the rate of said shaft, obviously the friction between the relatively moving surfaces is correspondingly reduced and the contacting parts bushing 33, in which case the idler gear 0| would As a result, less vibration is induced be mounted for free rotation either on said rotary hook shaft or the bushing.

The alternative embodiment illustrated in Figs. V-VII is exactly like the first described embodiment except in that the feed dog Ia receives its up and down movements from the rotating journal sleeve 32a for the rotary hook shaft 4a, the auxiliary shaft 3 having been eliminated. As

shown, the sleeve 32a is formed at its left hand end with an eccentric Zia/which, by means of the drop link 21a is coupled withthe downwardly and forwardly curved arm 28a of the feed bar 3a. Since all the other elements of the machine in Figs. V-VII have their counterparts in the first described embodiment, they have been identified with the same reference numerals previously employed with addition however in each case of the letter a for the purpose of distinction. The modified embodiment is obviously advantageous in instances where greater simplicity and compactness of structure is desired.

Having thus described our invention, we claim:

1. In a rotary hook sewing machine, a feed dog; three rotating shafts; a rotary hook secured to one of said shafts; and means on the other two shafts for respectively imparting the feed and lift movements to the feed dog. a

2. In a rotary hook sewing machine, a feed dog; three rotating shafts; a rotary hook secured to one of said shafts; and end cranks on the other two shafts for respectively imparting the feed and lift movements to the feed dog.

3. In a rotary hook sewing machine, a work support; a feed dog; three rotating shafts journaled beneath said work support; a rotary hook fixed to one of said shafts; and means on the other'two shafts for respectively imparting the feed and lift movements to the feed dog.

4. In a rotary hook sewing machine, a work support; a feed dog; three parallel rotary shafts journaled beneath said work support; drive means interconnecting the .three shafts; a rotary hook on the end of one of said shafts; and means on the corresponding ends of the other two shafts for respectively imparting the feed and lift movement to the feed dog.

5. In a rotary hook sewing machine, a feed dog three rotating shafts; a rotary hook secured to one of said shafts; means on the other two shafts for respectively imparting the feed and lift movements to the feed dog; a rotating sleeve in which the rotary hook shaft is journaled; means whereby the feed actuating shafts are driven in unison; and means whereby the rotary hook shaft is driven at a higher speed in the same direction as its journal sleeve.

6. In a rotary hook sewing machine, a feed dog; three rotating shafts; a rotary hook secured to one of said shafts; means on the other two shafts the transmission shaft; a feed dog supported with capacity for horizontal and up and down movements above the rotary hook and receiving its horizontal movement from said transmission shaft; an auxiliary shaft in the form of a sleeve surrounding the rotary hook shaft and driven from the transmission shaft; and means on said .15

sleeve for imparting up and down movements to the feed dog.

8. In a rotary hook sewing machine, a transmission shaft; a rotary hook shaft driven from said transmission shaft; a feed dog supported with capacity for horizontal and up and down movements above the rotary hook and receiving its horizontal movement from the transmission shaft; an auxiliary shaft in the form of a sleeve surrounding the hook shaft and driven in the same direction as the latter shaft from the transmission shaft; and means on the sleeve for imparting up and down movement to the feed dog.

9. In a rotary hook sewing machine, a transmission shaft; a rotary hook shaft driven from said transmission shaft at twice the speed of the latter; a feed dog supported with capacity for horizontal and up and down movements above the rotary hook and receiving its horizontal movement from said transmission shaft; an auxiliary shaft in the form of a sleeve surrounding the hook shaft and driven from the transmission shaft in the same direction-as said rotary hook shaft but at half the speed of the latter; and

- means on the sleeve for imparting up and down movement to the feed dog.

10. In a rotary hook sewing machine, a transmission shaft; a rotary hook shaft parallel with said transmission shaft driven by spur gears.

from the latter shaft; 9. feed dog supported with capacity for horizontal and up and down movements above the rotary hook and receiving its horizontal movement from the transmission shaft; an auxiliary shaft in the form of a sleeve surrounding the rotary hook shaft and also driven by spur gears from the transmission shaft in the same direction as said rotary hook shaft; and means on the sleeve for imparting up and down movement to the feed dog.

11. In a rotary hook sewing machine, a transmission shaft; a rotary hook shaft parallel with said transmission shaft and driven by spur gears from the latter shaft; 8. feed dog supported with capacity for horizontal up and down movements above the rotary hook and receiving its horizontal movement from the transmission shaft; an auxiliary shaft in the form of a sleeve surrounding the rotary hook shaft and driven by spur gears from the transmission shaft at half the sleeve;

speed of said rotary hook shaft in the same direction as the latter; and means on the sleeve for imparting up and down movement to the feed dog.

12. In a rotary hook sewing machine, a transmission shaft; a rotary hook shaft driven from said transmission shaft; a feed bar supporting a feed dog above the rotary hook; a rocker actuated by an eccentric on the transmission shaft to impart horizontal movement to the feed bar; an auxiliary shaft also driven from the transmission shaft; and an eccentric on said auxiliary shaft for imparting up and down movements to said feed dog connected by a link with the feed bar in line with the feed dog.

13. In a sewing machine, an element adapted to be moved in two directions at an angle to each other; a pair of shafts from which the two movements of said element are respectively derived; a

spur gear on each shaft; and an intermediate intermeshing idler gear whereby the two shafts are coordinated for rotation in the same direction.

14. In a sewing machine, a feed dog; a pair of shafts from which the feed and lift movements of the feed dog are respectively derived; identical spur gears respectively on the shafts; and an intermediate intermeshing idler gear whereby the two shafts are coordinated for rotation in the same direction.

15. In a sewing machine, a feed dog; a pair of shafts respectively with end cranks for imparting feed and lift movements to the dog; a spur gear on each shaft; and an intermediate intermeshing idler gear whereby the two shafts are coordinated for rotation in the same direction.

16. In a rotary hook sewing machine, a rotary hook shaft; a sleeve constituting the sole bearing for the rotary hook shaft; a journal for the and means for rotating the shaft and the sleeve simultaneously in the same direction but the latter at a slower rate than the first for the purpose of reducing the frictional resistance and heat generation between them at high speeds.

1'7. A sewing machine according to claim 16, in which the sleeve has direct bearing contact only at its ends with the hook shaft.

NORMAN V. CHRISTENSEN. GEORGE BAUER.

- CERTIFICATE OF CORRECTION.

Patent No. 2,216,700. October 1, 1911.0.-

NORHANV. CHRISTENSEN, ET AL.

It is hereby certified that error appearsin the printed specification of the above numbered patent requiring correction as follows: Page 1, first column, line 22, for the word "objection" read --in'vention--; page 2, second column, line 1 .5-h6, claim )4, for"movement" read --movements-; and

that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day or January, -A D. 19141.-

Henry Van Arsdale, (3 Acting Commissioner of Patents. 

